Odum's analysis was set up to compare the emergy used to build a cooling tower with the emergy value of losses to the ecosystem caused by releasing the effluent straight into the offshore waters. Emergy is a calculation of the energy previously used to create just about everything — from natural resources like coal or oil, to a finished product like a dining-room chair. In general, the emergy value corresponds to how many solar-energy units are used to create a product.

Essentially, Odum's analysis could thus provide an apples-to-apples comparison to help managers at Florida Power determine their next move. The professor found that the hot discharge had a temporarily negative effect on the surrounding waterways, disrupting plant life and sending fish scattering. The reason was that the heat was at first concentrated in one area.

But the ill effects dissipated quickly as the hot water swiftly circulated throughout the Gulf and its estuaries. The added flow and warmth increased the current, which enabled more fish to spawn and more sea grass to grow. Odum concluded that the power plant was giving back more emergy than it was taking from the environment.

On the other hand, Odum found, construction and ongoing maintenance of a cooling tower would eat up more emergy than the straight water- discharge method. The higher emergy value meant that a cooling tower would take more away from the local environs than it would give back.

But explaining the conclusion in court was futile because the emergy concept was too new and complex. Florida Power eventually settled out of court and built the cooling tower. Over the next two decades, emergy analyses were used to support several other environmental court challenges. But in each case the companies settled, eventually relegating the metric to academia.

In 2001, before he could see the United Nations and the U.S. Environmental Protection Agency apply emergy analysis to major policy initiatives, Odum died. Currently, however, the UN is working on a soil erosion project in North African countries, while the EPA just completed an emergy analysis of the state of West Virginia's economic and natural resources.

Screaming Economists
Indeed, it's hard to glimpse how blasphemous the concept seemed to economic traditionalists. Emergy lectures "used to send economists screaming from the room," quips Mark Brown, an associate professor of environmental-engineering sciences at the University of Florida who considers Odum his mentor. "Emergy questioned their core beliefs," asserts Brown in explaining why so many economists were bothered by the concept.

The uneasiness had philosophical roots. Emergy analysis relies on a donor system of valuation, rather than the traditionally accepted receiver system. Donor systems assign value based on how much energy, time, and material have been invested in a product or service, while a receiver system determines value by assessing what buyers are willing to pay for a product or service.

Receiver systems work well in a classic supply-and-demand marketplace, where price sets value. But when more comprehensive factors, such as the depletion and remediation of natural resources, are considered, a donor system like emergy is the better yardstick, contends Brown.

The emergy concept has been kicking around since the 1950s. Odum, then an Air Force meteorologist, observed how solar energy directly affected weather patterns. He also studied such indirect effects of the the sun's rays on such phenomena as tidal power and deep geological heat. His observations triggered a life-long pursuit of ways to compare different types of energy on a common basis.

That common denominator, according to Odum, is solar energy, the most basic energy component he could measure. Seen that way, emergy is Odum's blueprint for breaking down the world into basic, measurable energy components called solar emjoules. A joule is a unit of energy that is available now. An emjoule ("energy-embodied joule") represents an amount of energy invested in producing a specific product or providing a service.

Odum noted that emergy exists in a natural hierarchy that starts with solar energy and cascades down, capturing the energy-transformation processes it takes to produce a finished product — including all the environmental effects along the way. For instance, an emergy analysis of an oak table would comprise the emjoules picked up in growing the oak; cutting it down; shipping it to a mill; producing the boards; sending the lumber to a furniture factory; manufacturing and finishing the table; and shipping it to a retail outlet.

Leading Indicator
Over the last two decades, while the merits of emergy were being debated in court and at academic seminars, managers, investors, and activists were busy trying to quantify environmental and social issues in other ways. One prominent set of metrics to emerge from those attempts is the "sustainability reporting guidelines," developed in 1997 by the Global Reporting Initiative (GRI), a non-profit group based in Amsterdam.

To date, more than 700 companies worldwide — including Airbus, Dell, Fuji Film, GlaxoSmithKline, General Motors, Microsoft, and Nike — use the GRI guidelines, which track such factors as corporate energy usage, pollution emissions, child labor statistics, and health and safety records. In practice, the guidelines are broader than emergy's environmental focus.

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